1. Field of the Invention
The present invention relates to a circuit arrangement for telecommunication systems, particularly telephone exchange systems, comprising centralized and/or partially centralized, information-processing sequential logic systems having a limited call handling capacity with respect to the information processing capacity and comprising apparatus for identifying the information processing traffic load of a respective sequential logic system and for perceiving information processing traffic overloads and comprising counters serving to advert such overloads. The counters are incremented based on the measure of control signals appertaining to the traffic load and are deincremented at regular time intervals according to the information processing capacity and the attainment of a limiting value.
2. Description of the Prior Art
A circuit arrangement of this general type is disclosed in the German application No. 32 36 130. With the circuit arrangement disclosed in this application, overload signals are supplied to partially-centralized switching devices which supply information to a centralized information processing device for information processing, the overload signal being supplied thereto by the information processing device when its load capability limit with respect to traffic has been exceeded. The counters provided in the partially-centralized switching device therefore receive overload signals from the centralized information processing device. The overload problem, therefore, lies in the centralized information processing device. Averting overloads is carried out in the partially-centralized switching device. To this end, the latter receives overload signals from the centralized information processing device. The overload situation, therefore, is identified where it becomes a problem, namely in the centralized information processing device. The application does not state how this identification of the overload situation occurs; however, this is well known to those skilled in the art.
It was explained in a lecture at the "9th International Teletraffic Congress (ITC)" in October 1979 at Torremolinos, Spain (conference paper ITC-9 of Somoza et al, 1-7) for the recognition of the overload situation and the formation of overload signals that the number of requests arriving at a centralized computer are counted in individual time segments following successively upon one another and that the tally result thereby obtained each time is compared to a comparative value; this, moreover, is varied as a function of the respectively-existing operating situation. Every comparison result provides traffic information with respect to the question of the momentary computer traffic load, particularly regarding a potential overload. The number of computer requests and, therefore, the input information to be processed in the computer can be restricted or temporarily stopped entirely on the basis of the traffic load results acquired by counting in each of the time segments and identified by way of comparison after each conclusion of counting. The traffic load is thereby to be optimally matched to the call-handling capability and overload limits of the computer in order to achieve as high as possible a utilization of the computer capacity, as well as to avoid, insofar as possible, traffic overloads, these resulting, as known, in considerable, temporary operations restrictions or operations disruptions for the devices which use the computer. In the cases of use addressed in the lecture, therefore, this is improved by way of dynamic connection of the traffic load to the jobs of computing according to various types and, therein, according to the frequency of the jobs of computing supplied to the computer.
The known methods for proceeding and regulating the computer load, however, supply an adequately-precise result only when the individual time interval employed for counting the appertaining events, for example computer requests, is sufficiently large with respect to the mean chronological spacing between these events so that fluctuations in the computer traffic load, the load rising and falling continuously, do not cause the computer traffic load to be represented in coarse skips so that a corresponding control is capable of optimally matching the computer traffic load to the load capacity. The requirement inherent therein, namely that the time interval for the individual tally of the events must be sufficiently large, has a negative effect on the respective time at which the results of each of the tally operations are available. The result of identifying the computer traffic load, therefore, still always exhibits a time lag that is necessarily conditioned by the fact that the corresponding result for each acquisition time interval is identified only after the time interval has elapsed, being identified, in particular, by way of a comparison operation. This time lag is, in turn, disadvantageous to influencing the computer traffic load for the purpose of regulating the load. For, in particular, either averting an overload can only take effect when the overload situation has already occurred, i.e. too late in view of actually arising overloads, or the aversion of an overload must already begin before the overload limit of the computer has been reached, i.e. "under suspension", thus not only in those operating instances in which the computer traffic load in fact rises above the loadability limit, rather, in addition, in all of those operating instances as well in which the rise of the computer traffic load in the direction towards the loadability limit only produces the assumption that the loadability limit will be transgressed, but in which the computer traffic load does not in fact reach or exceed the loadability limit. The problem therefore lies in the extrapolation of the load behavior over the time. A regulation, however, is less and less effective the later it begins; its relatively late beginning, in addition, can result in the fact that periods of more-pronounced under-utilization alternate continuously with periods of overload without this being actually caused by the traffic load that in fact occurs. The mentioned requirement is further intensified by the condition that the chronological distribution of the events to be acquired scatters noticeably, that, therefore, the chronological spacings between the respectively-successive events are relatively unequal in comparison to one another. This effect is all the more aggravating the smaller the respective acquisition range; the greater the range is, in particular, the greater the influence of the compensating effect of the statistical distribution. This generally testifies in favor of providing the implemented identification of the overload situation at a central location.